In 2004, Seol moved to England, joining Championship club Wolverhampton Wanderers. He made over 30 appearances by the end of the 2004–05 season, scoring a few goals too. The Wolverhampton coach at the time, Glenn Hoddle, preferred Seol as one of his first-choice strikers, using him in a wide, supporting role to the main strikers.

Disappointed with the failure of Wolves to win promotion from The Championship, Seol sought a move to the Premier League following the 2006 FIFA World Cup, despite having two years of his contract left. He was reported as saying "At this stage, I'm frustrated not to be in the Premiership. I think there will be some good news after the World Cup."[1]

Seol eventually joined newly promoted Premier League club Reading on 12 July 2006 for a fee of £1 million (rising to £1.5 million based on certain criteria).[2] He scored his first Premiership goal as Reading won 2–1 at Sheffield United on 16 September 2006.[3] He scored his second goal for Reading against West Ham United, proving to be only goal of the match.[4] His third goal for Reading, his first at home, came on 18 November 2006 in the 2–0 win against Charlton Athletic.[5] He scored his fourth goal against Blackburn, the last game of the season.

Seol left Reading for Fulham on 31 August 2007 for an undisclosed fee on a three-year contract, with Liam Rosenior going the other way.[6] Reading boss Steve Coppell admitted that strained relations between him and Seol led to the move.[7] At the time of his Fulham career, Seol wrote on his blog on the club's official website, where he has "been living in Sutton in Surrey for a few months now with his family. There’s actually a big Korean community nearby".[8] He did not score his first goal for Fulham until 16 August 2008 against Hull City, despite Fulham eventually losing 2–1.[9] Seol signed an initial 6-month loan move to Al-Hilal in Saudi Arabia with a view to a permanent move on 14 January 2009[10] Seol stated he desired to stay at Fulham to win his place in the squad,[11] and he went on to score his second goal for the club against FK Vetra in the Europa League.[12] In January 2010, to increase first-team football playing time and to improve his chance to be included in the Korean last-23 in 2010 FIFA World Cup, Seol engaged in loan talks with the Hong Kong First Division Club South China[13] but no deal was agreed. It was announced on 15 January that Seol Ki-Hyeon's contract with Fulham had been cancelled by mutual consent.[14]

Seol plays for South Korea internationally. He played in his first World Cup in front of his home crowd, South Korea being co-hosts with Japan for the 2002 finals. Seol was a key member of the South Korea squad during the tournament, memorably scoring the equalising goal against Italy in the knock-out stages.[15]

Seol was voted by Reading fans as the official Player of the Month for August[16] and September 2006. Seol played in all three of the Royals' Premiership games in August when he helped to create three of the four goals scored.